Cellulose ester textile materials



United States Patent Cfiice 3,369,916 Patented Feb. 20, 1968 1 Claim. Cl. 106-181) ABSTRACT OF THE DISCLOSURE Cellulose acetates, both secondary and triacetates, are rendered more resistant to delustring by incorporating in textile articles made from them 0.1 to 5% (on the weight of the cellulose acetate) of orthophthalic, isophthalic, terephthalic, trimesic or adipic acid. The articles can be made by dry spinning solutions of the cellulose acetate containing the additive.

This application is a continuation-in-part of 416,148 filed Dec. 4, 1964, now abandoned.

This invention relates to textile materials comprising fibres of cellulose acetates having improved resistance to delustring.

It is well known that fibres of cellulose acetates tend to become delustred, i.e. to acquire a more or less dull or opalescent appearance, when they are treated in aqueous baths at high temperatures.

The conditions under which this effect starts to manifest itself vary in accordance with the nature and origin of the acetate employed, and notably in accordance with its degree of acetylation. In fibres of secondary cellulose acetates, the effect begins to appear generally between 80 and 85 C., while in fibres of the so-called cellulose triacetates (i.e. cellulose acetates having a combined acetic acid content above 59%), the effect appears only at much higher temperatures, which may even be above 100 C. in some cases.

Various means are known for avoiding or lessening the delustring of cellulose acetate fibres in aqueous baths at high temperatures, for example the addition of protective salts to the said baths, or replacement of the cations retained as impurities in the cellulose acetate from its production.

It has now been discovered that fibres of cellulose acetates sensitive to delustring in aqueous baths at high temperatures may be improved in this respect without modifying the cellulose acetate spun or the spinning operation, by adding to the spinning solution a small proportion of certain acids.

Accordingly in one aspect this invention consists in textile articles comprising threads'or fibres of cellulose esters and containing between 0.1% and 5% by weight of at least one acid of the general formula R(COOH),,, in which R is a hydrocarbyl radical of 4 to 6 carbon atoms, and n is 2 or 3.

Also in accordance with the invention threads and fibres of cellulose acetates which are unusually resistant to delustring are made by extruding in the form of fibres a solution of a cellulose acetate containing 0.1-5%, of the weight of the cellulose acetate, of an acid of formula R(COOH),,, in which R is a hydrocarbyl radical of 4-6 carbon atoms and n is an integer from 2 to 3, and setting the fibres so formed by evaporation of the solvent (dry spinning).

The term cellulose acetates is used to denote both socalled secondary cellulose acetates having a combined acetic acid content between 54.5% and 55%, and the product commonly called cellulose triacetate, having a combined acetic acid content between 59% and 61.5%.

Among the acids of formula R(COOH),,, with which good results have been obtained, there may be mentioned orthophthalic acid, isophthalic acid, terephthalic acid, adipic acid and trimesic acid. In some cases, these products may be introduced in the form of their anhydrides, the moisture present in the spinning solution generally being sufficient to convert them to the acids.

The extent to which the delustring threshold temperature is raised varies with the acetate employedand the spinning process.

In the case of dry spin secondary acetate fibres, it is possible to raise the delustring threshold temperature by from 2 to 5 C., depending upon circumstances; although this increase is small in absolute terms, it is of great technological importance, since, as is well known, secondary cellulose acetates commence to dye effectively at about C., and even a slight increase in the margin of safety from the viewpoint of delustring not only makes it possible-to improving the depth and levelness of the dyeing, but also provides an important increase in the safety factor with regard to accidental damage due to delustring effect.

In the case of dry spun fibres of cellulose triacetates, the increase in the temperature at which delustring begins may in some cases be as much as 30 C.; this is clearly important, especially in the case of articles which start to become delustred at about 105 C. and which may, by means of the present invention, be treated without delustring at temperatures of about C., and possibly higher, so enabling these articles to be subjected to the thermal treatments necessary for producing good noncreasing properties, as well as to be dyed under optimum conditions.

It is also found that different acids exercise their greatest effect, and are preferably employed in association with, either cellulose triacetates or secondary cellulose acetates but not both. Orthophthalic acid is an exception, being very effective, in raising the delustring threshold temperature of both types of cellulose acetate, and is indeed particularly preferred for use in accordance with the invention. On the other hand, the terephthalic acid and trimesic acid, for example, are most effective with secondary cellulose acetates, while isophthalic acid and adipic acids are most effective with cellulose triacetates. The type of cellulose acetate in association with which any particular acid is most effective is readily determined by a simple test.

The following examples illustrate without limiting the invention.

EXAMPLE 1 A solution of 21.5% by weight of cellulose triacetate in a mixture of methylene chloride and methanol (90/10 by weight) is dry spun in a known way to give threads which begin to delustre at 100 C. When 0.2% of orthophthalic acid (calculated on the weight of triacetate) is added to the same solution, which is then spun under the same conditions as before, there is obtained a thread which remains shiny when treated with hot water under pressure up to and even above 130 C., a rise in the delustring threshold temperature of at least 30 C.

The threads thus obtained and the control threads are used to make fabrics for blouses. As is usual with triace- 1 EXAMPLES 7 to 12 spinning, the following results were obtained:

tate fabrics, these fabrics are dyed in an aqueous bath at 130 C., this temperature sufficing both to give good depth TABLE II of dyeing and also to render the fabric crease resistant. It is found that the fabric made with the control thread Quantities Delusmng Appearance of Breaking is dull, while that made with the thread containlng ortho- Examples of and th s th thr ad streucth phthalic acid has remained shiny. If it is desired to mainggg f g 32??? 3695 tain the fabric made of the control thread in the shiny condition, it IS necessary to keep the temperature to a 0 82 opalescenthm L32 maximum of 100 C., but 1n this case the intensity of the 7 0.1 85-90 Very slightly 1. 32 shade obtained is lower and the fabric is not crease re- 02 85% opalescent' 1 33 sistant. 0. 4 85-90 1. 37

The following table shows the serirnetric results ob- 3-2 36 kg? tained on the control thread and on the thread containing 32 90 1.06 the orthophthalic acid.

Breaking strength in g./d. Elongation at rupture Treatment undergone by the Reference Addition of Reference Addition of iread product ort oproduct, orthophthalic percent phthalic acid acid, percent Untreated 1. 15 1. 34 36 Steaming min. at 130 C 1.10 1.12 32 34. 8 Pressurised water 1 hour at 120 O 1. 08 1. 11 32. 2 32. 6 Heat treatment 24 hours at 110 C- 1. 12 1. 17 32. S 37 It will clearl be seen from this table that the serimetic y EXAMPLE 13 properties are slightly improved by the presence of orthophthalic acid.

The following table, which relates to the action of light, shows comparative tests carried out with and without introduction of 0.2% of orthophthalic acid by exposure to light in an apparatus known under the trade mark Xenotest, for 158 hours.

affords protection against degradation by light.

EXAMPLES 2 to 6 The same cellulose triacetate spinning solution is employed as in Example 1, and variable quantities of orthophthalic acid are introduced. After dry spinning, the following results were obtained:

TABLE I Quantities Delustring Appearance of Breaking Examples of acid threshold the thread resistance (percent) temperatreated with in gJd.

ture, 0. water at 130 C.

1. 6 110 Slightly opal- 1. 23

escent. 3.2 110 ...do 1,17

EXAMPLE 14 An acetone solution of a secondary cellulose acetate containing 0.1% of trimesic acid calculated on the weight of the cellulose acetate, is dry-spun by known means. A thread is obtained which becomes very slightly opalescent under the action of water at -90 C., while a control of the same acetate thread becomes distinctly opalescent at 82 C.

EXAMPLE 15 The same cellulose triacetate solution as in Example 1, but containing 0.2% of isophthalic acid on the weight of the cellulose triacetate, is dry-spun by known means. A thread is obtained which becomes slightly opalescent under the action of water at 105 C., while a control thread starts to become opalescent at C.

EXAMPLE 16 The same cellulose triacetate solution as in Example 1, containing 0.1% of adipic acid, is dry-spun by known means. A thread is obtained which is very slightly opalescent from -110 C., while a control thread starts to become opalescent at 100 C. These last examples 6 show that isophthalic and adipic acids, while they are References Cited most effective with secondary cellulose acetates, have UNITED STATES PATENTS some effect also With triacetates. 2 040 971 5 9 Auden 106 131 We clalym 2,065,766 12/1936 Taylor 106-481 1. Textxle artlcles compnslng fibres of cellulose tn- 5 2 39 024 11 1945 Bruson 106 181 acetate which fibres contain 0.1 to 3.2% by Weight of orthophthalic acid. JULIUS FROME, Primary Examiner. 

